On the Analysis of Damping in Elastic-plastic Inhomogeneous Beams

This paper describes an analytical approach for analyzing of the total damping energy for a continuously inhomogeneous elastic-plastic beam structure subjected to cyclic axial forces. The mechanical behaviour of the material is treated by using a cyclic stress-strain curve of the Ramberg-Osgood form. The beam cross-section is a rectangle. The material properties are distributed continuously along the height of the beam cross-section. The unit damping energy is integrated in the beam volume in order to derive the total damping energy. The analytical solution obtained is applied to carry-out a parametric study of the total damping energy in the beam structure.

Stress calculation method of bending multilayer structural element when bending moment acts in the planes that do not coincident with principal planes

This paper presents stress calculationmethod of bending multilayer structural element when bending moment acts in the planes that do not coincident with principal planes, and cross section is symmetric or asymmetric. Carrying the computation of occurring stress values in multilayer beam layers it is necessary to identify coordinates of cross-section stiffness centre, direction of principal axes, and coordinates of specific points regarding principal axes. Having this information and equation which is valid for stress calculation of bending multilayer beams it is possible to identify normal stress values at any point of the beam cross section under skew bending. It is deduced that stress values and the nature of their changes are influenced by the shape of beam cross-section, its asymmetry degree, and the direction of appliedmoment.

Laguerre-Gaussian modes generated vector beam via nonlinear magneto-optical rotation

Laguerre-Gaussian (LG) beams contain a helical phase front with a doughnut-like intensity profile. We use the LG beam to introduce a rather simple method for generation of a vector beam (VB), a beam with spatially-dependent polarization in the beam cross section, via the nonlinear magneto-optical rotation (NMOR). We consider the NMOR of the polarization of a linearly polarized probe field passing through an inverted Y-type four-level quantum system interacting with a LG control field and a static magnetic field. It is shown that the polarization of the transmitted field is spatially distributed by the orbital angular momentum (OAM) of the LG control field, leading to generation of the VB with azimuthally symmetric polarization distribution. We show that the polarization and intensity distributions of the VB spatially vary by changing the OAMs of the LG control field. Moreover, the radial index of the LG control field has a major role in more spatially polarization distributing of the VB. It is shown that the intensity of the generated VBs in different points of the beam cross section can be controlled by the OAM as well as the radial index of the LG control field. However, the VB with highly spatially distributed can be generated for higher values of the radial index of LG control field. The analytical calculations determine the contribution of the different nonlinear (cross-Kerr effect) phenomena on the generation of the VB. We show that the VB is mainly generated via birefringence induced by the applied fields. Finally, we use asymmetric LG (aLG) beams for making the VBs with asymmetric polarization distribution. It is shown that by applying aLG beams, the azimuthal symmetry of the polarization distribution breaks and the asymmetric polarization distribution can be controlled by OAM and radial index of the aLG control field. The obtained results may find more interesting applications in fiber/free space optical communication to enhance the capacity of the information transmission.

Study of Topology Optimized Hammerhead Pier Beam Made with Novel Preplaced Aggregate Fibrous Concrete

This study aims to study topology Optimized Hammerhead Pier Beam (TOHPB) designed with a density-based technique. TOHPB is made with Preplaced Aggregate Fibrous Concrete (PAFC), which comprises two main preparation processes. First, the fibers and coarse aggregates filled into empty formwork to develop a skeletal system. Second, voids in the skeletal system are filled with cement grout; hence a type of PAFC was obtained. Besides, alleviating the self-weight of the concrete beam is a top priority of design engineering without compromising its strength and durability. The effect of topology optimization in association with the safety of factors and elastic design case is considered in this study. Explicitly, (i) compliance is scaled down to a minimum under a perimeter on the utilized material (ii) the principle Drucker-Prager is employed to impose the stress limitations even though utilization of material is minimized. The problem is designed with imposed stress limitation and generates keys that involve an essential part of post-processing before fabrication. In total, ten TOHPB were prepared with and without the combined shape of crimped-hooked end steel fiber. Two different types of fiber reinforcement schemes were used; first, the fibers were reinforced to full beam cross-section; then, the fibers were reinforced to the top half of the beam cross-section. Results revealed that the TOHPB beam reinforced full cross-section exhibited better ultimate load performance than that of the beam with half reinforced cross-section.

Introducing Design Space-Independence in Beam Cross-Section Optimization

The cross-sectional topology optimization of a slender load carrying member such as a beam typically begins with the choice of design space which is generally either a square or a rectangle. However, when subjected to bending and torsional loads, such design space may often lead to biased topologies as the material distribution is directed towards the boundaries. As it may be difficult to avoid square/rectangular design space, this work introduces a constraint which may help in decreasing the dependency on the shape of the design space. The constraint is on polar first moment of area and is different from the traditional weight constraint in a way that it simultaneously constrains the weight and enclosed volume. The outcomes from the new scheme are compared with those obtained through conventional compliance- and weight- based topology optimization formulation.

Searching for a Global alpha-nucleus Potential for Astrophysical Applications

This contribution reports on a systematic investigation of in-beam cross-section measurements of (α,γ) reactions, carried out using a 4π calorimeter. The results are compared to the predictions of the Hauser-Feshbach (HF) theory. This com­ parison puts some constraints on the relevant nuclear properties entering the HF calculations.

Investigation of a Cross-Section with a Constant Transverse Shear Stress Distribution Using a Numerical Approach

A structural beam which is subjected to shear forces acting perpendicularly to its longitudinal axis will experience longitudinal and transverse shear stresses. In beams where failure in the transverse direction is plausible, it is desirable to maintain a constant transverse shear stress over the beam cross-section to avoid stress concentrations and to use the least amount of material. A numerical approach to the inverse problem of solving for a beam cross-section with a constant transverse shear stress distribution was investigated in this study using Microsoft Excel’s Solver and Matlab. The efficiency and shape of the developed cross-section were dependent on the number of elements used to discretize the cross-section. As the number of elements approached infinity, the shape of the cross-section became infinitely thin at the top and infinitely wide at the neutral axis, while also approaching an efficiency of 100%. It is therefore determined that this is an ill-posed inverse problem and no such perfect cross-section exists.